T. Kobayashi
A5108058077- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Nuclear physics research studies
- Astrophysics and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Nuclear Physics and Applications
- High-Energy Particle Collisions Research
- Dark Matter and Cosmic Phenomena
- Astronomical and nuclear sciences
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- Radiation Detection and Scintillator Technologies
- Microstructure and Mechanical Properties of Steels
- Advanced Chemical Physics Studies
- Advanced NMR Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Molecular Junctions and Nanostructures
- Metal Alloys Wear and Properties
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
Tohoku University
2014-2024
The University of Tokyo
2014-2024
GSI Helmholtz Centre for Heavy Ion Research
2020-2024
High Energy Accelerator Research Organization
2014-2023
Japan Proton Accelerator Research Complex
2016-2023
RIKEN Nishina Center
2013-2023
Université Paris-Saclay
2019-2022
Institut de Recherche sur les Lois Fondamentales de l'Univers
2019-2022
CEA Paris-Saclay
2019-2022
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2019-2022
We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure the Super-Kamiokande detector. The exhibit zenith angle dependent deficit muon neutrinos which is inconsistent with expectations based on calculations flux. Experimental biases and uncertainties in prediction fluxes cross sections are unable to explain our observation. consistent, however, two-flavor...
Solar neutrino measurements from 1258 days of data the Super-Kamiokande detector are presented. The based on recoil electrons in energy range 5.0--20.0 MeV. measured solar flux is $2.32\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{stat}{)}_{\ensuremath{-}0.07}^{+0.08}(\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{6}{\mathrm{cm}}^{\ensuremath{-}2}{\mathrm{s}}^{\ensuremath{-}1}$, which $45.1\ifmmode\pm\else\textpm\fi{}0.5(\mathrm{stat}{)}_{\ensuremath{-}1.4}^{+1.6}(\mathrm{syst})%$ that...
The K2K experiment observes indications of neutrino oscillation: a reduction $\nu_\mu$ flux together with distortion the energy spectrum. Fifty-six beam events are observed in Super-Kamiokande (SK), 250 km from production point, an expectation $80.1^{+6.2}_{-5.4}$. Twenty-nine one ring $\mu$-like used to reconstruct spectrum, which is better matched expected spectrum oscillation than without. probability that at SK explained by statistical fluctuation without less 1%.
We present a combined analysis of fully-contained, partially-contained and upward-going muon atmospheric neutrino data from 1489 d exposure the Super-Kamiokande detector. The samples span roughly five decades in energy, 100 MeV to 10 TeV. A detailed Monte Carlo comparison is described presented. fit expectation, found be consistent with oscillations ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\leftrightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ ${sin}^{2}2\ensuremath{\theta}>0.92$...
The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. shown here obtained data taken between 31 May 1996, and 23 June 1997. Using our recoil electrons with energies above 6.5 MeV, we infer total ${}^{8}\mathrm{B}$ neutrinos to be $2.42\ifmmode\pm\else\textpm\fi{}0.06(\mathrm{stat}{)}_{\ensuremath{-}0.07}^{+0.10}(\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{6}\mathrm{cm}{}^{\ensuremath{-}2}{\mathrm{s}}^{\ensuremath{-}1}$. This result is...
We present measurements of nu_mu disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One hundred and twelve beam-originated events are observed fiducial volume Super-Kamiokande with an expectation 158.1^{+9.2}_{-8.6} without oscillation. A distortion energy spectrum is also seen 58 single-ring muon-like reconstructed energies. The probability that observations explained by for no 0.0015% (4.3sigma). In a two flavor scenario, allowed Delta m^2 region at...
We report the result of a search for neutrino oscillations using precise measurements recoil electron energy spectrum and zenith angle variations solar flux from 1258 days neutrino-electron scattering data in Super-Kamiokande. The absence significant variation distortion places strong constraints on mixing mass difference flux-independent way. Using Super-Kamiokande measurement addition, two allowed regions at large are found.Received 19 March...
Muon neutrino disappearance probability as a function of flight length L over energy E was studied. A dip in the L/E distribution observed data, predicted from sinusoidal flavor transition oscillation. The constrained nu_mu <-> nu_tau oscillation parameters; 1.9x10^-3 < Delta m^2 3.0x10^-3 eV^2 and \sin^2(2theta) > 0.90 at 90% confidence level.
A total of 614 upward throughgoing muons minimum energy 1.6 GeV are observed by Super-Kamiokande during 537 detector live days. The measured muon flux is [1.74±0.07(stat)±0.02(sys)]×10−13cm−2s−1sr−1 compared to an expected [1.97±0.44(theor)]×10−13cm−2s−1sr−1. absolute in agreement with the prediction within errors. However, zenith-angle dependence does not agree no-oscillation predictions. distortion shape consistent νμ↔ντ oscillation hypothesis sin22θ>0.4 and 1×10−3<Δm2<1×10−1eV2 at 90%...
From an exposure of 25.5 kiloton-years the Super-Kamiokande detector, 900 muon-like and 983 electron-like single-ring atmospheric neutrino interactions were detected with momentum pe>100 MeV/c, pμ>200 visible energy less than 1.33 GeV. Using a detailed Monte Carlo simulation, ratio (μ/e)DATA/(μ/e)MC was measured to be 0.61±0.03(stat.)±0.05(sys.), consistent previous results from Kamiokande, IMB Soudan-2 experiments, smaller expected theoretical models production.
We present results for ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillation in the KEK to Kamioka (K2K) long-baseline neutrino experiment. K2K uses an accelerator-produced beam with a mean energy of 1.3 GeV directed at Super-Kamiokande detector. observed energy-dependent disappearance ${\ensuremath{\nu}}_{\ensuremath{\mu}}$, which we presume have oscillated ${\ensuremath{\nu}}_{\ensuremath{\tau}}$. The probability that would observe these if there is no 0.0050% ($4.0\ensuremath{\sigma}$).
The details of Super-Kamiokande-I’s solar neutrino analysis are given. Solar measurement in Super-Kamiokande is a high statistics collection 8B neutrinos via neutrino-electron scattering. method and results the 1496 day data sample presented. final oscillation for presented also.50 MoreReceived 30 August 2005DOI:https://doi.org/10.1103/PhysRevD.73.112001©2006 American Physical Society
The results of the second phase Super-Kamiokande solar neutrino measurement are presented and compared to first phase. flux spectrum time variation as well oscillation statistically consistent with do not show spectral distortion. time-dependent combined phases coincides full period cycle 23 shows no correlation activity. measured $^{8}\mathrm{B}$ total is...
The flavor ratio of the atmospheric neutrino flux and its zenith angle dependence have been studied in multi-GeV energy range using an exposure 25.5 kiloton-years Super-Kamiokande detector. By comparing data to a detailed Monte Carlo simulation, (μ/e)DATA/(μ/e)MC was measured be 0.66±0.06(stat.)±0.08(sys.). In addition, strong distortion shape μ-like event distribution observed. number upward downward events found 0.52+0.07−0.06(stat.)±0.01(sys.), with expected value...
The results of the third phase Super-Kamiokande solar neutrino measurement are presented and compared to first second results. With improved detector calibrations, a full simulation, analysis methods, systematic uncertainty on total flux is estimated be ?2.1%, which about two thirds for Super-Kamiokande. observed 8B in 5.0 20 MeV electron energy region 2.32+/-0.04 (stat.)+/-0.05 (sys.) *10^6 cm^-2sec^-1, agreement with previous measurements. A combined oscillation carried out using SK-I, II,...
Projectile fragmentations of $^{11}\mathrm{Li}$, $^{8}\mathrm{He}$, and $^{6}\mathrm{He}$ have been measured at 0.79 GeV/nucleon. Production cross sections momentum distributions the produced isotopes ($Z\ensuremath{\ge}2$) are inclusively. Transverse-momentum $^{9}\mathrm{Li}$ from fragmentation $^{11}\mathrm{Li}$ show two Gaussian components different widths. The width wide component is consistent with values observed in stable nuclei, whereas other shows an extremely narrow reflecting...
We present a search for non-zero theta_{13} and deviations of sin^2 theta_{23} from 0.5 in the oscillations atmospheric neutrino data Super-Kamiokande -I, -II, -III. No distortions flux consistent with are found both mass hierarchy hypotheses agreement data. The best fit at Delta m^2 = 2.1 x 10^-3 eV^2, 0.0, =0.5. In normal (inverted) constrained one-dimensional 90% C.L. to < 0.04 (0.09) 1.9 (1.7) 2.6 (2.7) eV^2. mixing angle is within 0.407 <= 0.583
After important upgrades to the experiment, Super-Kamiokande collaboration returns measuring solar mixing angle and mass splitting $\mathrm{\ensuremath{\Delta}}\phantom{\rule{0}{0ex}}{m}_{12}^{2}$. By focusing on low-energy ${}^{8}B$ neutrinos, is able single out neutrinos that undergo flavor conversion only through vacuum oscillations. The results are currently most precise values for mass-difference parameters relevant neutrino
Super-Kamiokande (SK) can search for weakly interacting massive particles (WIMPs) by detecting neutrinos produced from WIMP annihilations occurring inside the Sun. In this analysis, we include neutrino events with interaction vertices in detector addition to upward-going muons surrounding rock. Compared previous result, which used only, signal acceptances light (few−GeV/c2−200−GeV/c2) WIMPs are significantly increased. We fit 3903 days of SK data contribution annihilation found no...